The loneliest gun store in Mexico

In this July 15, 2016 photo, customers look over guns available for purchase at the country's lone gun store in Mexico City. Those who enter must surrender any cellphones, tablets or cameras, remove caps and pass through a metal detector. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, a customer looks over rifles available for purchase at the country's lone gun store in Mexico City. The shop averages about 40 gun sales every day. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, customers look over guns available for purchase at the country's lone gun store in Mexico City. The store sold 549 guns in 2000. For 2015, sales rose to 10,115 guns, an increase reflecting the rise in concern about personal safety. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, a customer looks over rifles available for purchase at the country's lone gun store in Mexico City. The store is run by soldiers in an anonymous building on a secure army base, and it's prohibited from advertising its wares or even its existence. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, a customer validates his purchase with a soldier before exiting the country's lone gun store in Mexico City. The Geneva-based Small Arms Survey says Mexicans owned 15.5 million firearms in 2007, of which 4.5 million were properly registered with the army. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, a Glock pistol is stamped with a marking signifying the gun was purchased from the Army's lone gun store in Mexico City. All firearms must be registered with the Army to be considered legally owned. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, a semi-automatic rifle is stamped with a marking signifying the gun was imported by the Army's lone gun store and is available to be purchased by select security personnel in Mexico City. Mexico's constitution guarantees citizens' right to own a handgun and hunting rifles for self-defense and sport. (AP Photo/Nick Wagner) (WagnerPhotos)

In this July 15, 2016 photo, Army Col. Eduardo Tellez Moreno who is the director of the country's lone gun store in Mexico City poses for a photo. Mexicans can legally purchase one handgun for home protection, while members of hunting or shooting clubs can acquire up to nine rifles of no more than .30 caliber and shotguns up to 12 gauge, said Tellez Moreno, but he would prefer that no one buy what he's selling. (AP Photo/Nick Wagner) (WagnerPhotos)